1// Copyright 2019 The Prometheus Authors 2// Licensed under the Apache License, Version 2.0 (the "License"); 3// you may not use this file except in compliance with the License. 4// You may obtain a copy of the License at 5// 6// http://www.apache.org/licenses/LICENSE-2.0 7// 8// Unless required by applicable law or agreed to in writing, software 9// distributed under the License is distributed on an "AS IS" BASIS, 10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 11// See the License for the specific language governing permissions and 12// limitations under the License. 13 14package procfs 15 16import ( 17 "fmt" 18 "io/ioutil" 19 "net" 20 "strings" 21) 22 23// ARPEntry contains a single row of the columnar data represented in 24// /proc/net/arp. 25type ARPEntry struct { 26 // IP address 27 IPAddr net.IP 28 // MAC address 29 HWAddr net.HardwareAddr 30 // Name of the device 31 Device string 32} 33 34// GatherARPEntries retrieves all the ARP entries, parse the relevant columns, 35// and then return a slice of ARPEntry's. 36func (fs FS) GatherARPEntries() ([]ARPEntry, error) { 37 data, err := ioutil.ReadFile(fs.proc.Path("net/arp")) 38 if err != nil { 39 return nil, fmt.Errorf("error reading arp %q: %w", fs.proc.Path("net/arp"), err) 40 } 41 42 return parseARPEntries(data) 43} 44 45func parseARPEntries(data []byte) ([]ARPEntry, error) { 46 lines := strings.Split(string(data), "\n") 47 entries := make([]ARPEntry, 0) 48 var err error 49 const ( 50 expectedDataWidth = 6 51 expectedHeaderWidth = 9 52 ) 53 for _, line := range lines { 54 columns := strings.Fields(line) 55 width := len(columns) 56 57 if width == expectedHeaderWidth || width == 0 { 58 continue 59 } else if width == expectedDataWidth { 60 entry, err := parseARPEntry(columns) 61 if err != nil { 62 return []ARPEntry{}, fmt.Errorf("failed to parse ARP entry: %w", err) 63 } 64 entries = append(entries, entry) 65 } else { 66 return []ARPEntry{}, fmt.Errorf("%d columns were detected, but %d were expected", width, expectedDataWidth) 67 } 68 69 } 70 71 return entries, err 72} 73 74func parseARPEntry(columns []string) (ARPEntry, error) { 75 ip := net.ParseIP(columns[0]) 76 mac := net.HardwareAddr(columns[3]) 77 78 entry := ARPEntry{ 79 IPAddr: ip, 80 HWAddr: mac, 81 Device: columns[5], 82 } 83 84 return entry, nil 85} 86